According to a sharp increase in traffic of high-speed data communication in a wireless or mobile communication system, research on Beam Division Multiple Access (BDMA) system has been actively performed in a next-generation communication system.
Currently, carrier frequencies, that major domestic communication operators are using, are in approximately 2 GHz band. Hardware elements forming a communication system are configured in view of a narrow band system, and it is typical that the narrow band system conventionally uses approximately ⅛ to 1/10 of the system carrier frequencies as a bandwidth. Accordingly, currently, the narrow band system is using a maximum of a bandwidth of approximately 200 MHz with a carrier frequency in the 2 GHz band as a reference. However, as mobile data traffic explosively increases due to the recent diffusion of smart phones and the like, a wide bandwidth is required. To this end, research on carrier frequencies in 28 to 30 GHz band, which is ten or more times higher than the current carrier frequency band, is being performed.
Meanwhile, reception power is proportional to the square of a wavelength, and is inversely proportional to the square of a distance. Accordingly, when a carrier frequency increases ten times, the wavelength of a carrier is reduced by 1/10, and thus the reception power is reduced by 1/100 with an identical distance as a reference. As a result, when a carrier in a high frequency band is used as described above, severe signal attenuation occurs in a receiver. In order to overcome the signal attenuation, a method is influential for reducing the size of a base station cell, and generating a beam maximizing a Signal-to-Noise Ratio (SNR) and performing communication when a signal is transmitted/received between a base station and a user equipment. Accordingly, the user equipment needs to find a base station maximizing an SNR among multiple base stations which are denser than in an existing communication system, needs to find a beam maximizing a SNR with the relevant base station, and needs to communicate with the base station by using the beam. These situations become a basic premise in the BDMA system.